fredag 25 juni 2010

AGW alarmism is based on an idea of "back radiation" or "re-radiation" from an atmosphere with greenhouse gases, but the physics of this phenomenon remains unclear.

To test if "back radiation" is a real phenomenon, we suggest the following experiment: On a night with moon-light so feeble that you can cannot read a newspaper, place yourself in front of a mirror letting the moonlight reflect from the newspaper to the mirror and back again, and check if you can now read. You will probably find that the paper is still unreadable, as if "back radiation" does not give more light.

To give this experiment theoretical support we consider the mathematics of wave propagation from a source at x=0 (Earth surface) to a receiver at x=1 (atmospheric layer) described by the wave equation (as a model of Maxwell's equations describing light as electromagnetic waves):

U_tt - U_xx = 0 for x in the interval (0,1)

with solution U(x,t) being a combination of waves traveling with velocity +1 and -1 along the x-axis, and with subindices indicating differentiation with respect to space x and time t. The boundary condition at the receiver may take the form

AU_t(1,t) + U_x(1,t) =0

with a positive coefficient A signifying:

A = 0: soft reflection with U_x(1,t) = 0

A large : hard reflection with U_t(1,t) = 0

A = 1: no reflection: transparent absorption of all incoming waves at x = 1.

The basic energy balance is obtained by multiplying the wave equation by U_t and integrating

with respect to x to give:

E_t + AU_t(1,t)^2 = -U_x(0,t)U_t(0,t) = Input Energy.

where E(t) is the energy of the wave over the interval (0,1). Assuming that E(t) stays constant so that energy is no accumulating in the interval (0,1), we have that

Output Energy = A U_t(1,t)^2 = Input Energy.

In particular, with soft reflection with A = 0, the Input Energy is also zero. We learn that it is not possible to "pump the system" by reflection at x = 1: If you change from transparency with A = 1 to reflection with A = 0, the system reacts by refusing to accept Input Energy.

This conforms with the relation dQ ~ 4 dT which follows from differentiating Stefan-Boltzmann's Q = c T^4, as we have discussed in previous posts.

Is this an indication that real climate sensitivity is about 1 C upon doubling of atmospheric CO2?

Maybe, maybe not: It requires that

(i) doubled CO2 gives a forcing of about 4 W/m2

(ii) the effect of the Pinatuba eruption with increasing aerosols in the stratosphere reducing incoming radiation, can be translated to a CO2 effect in the troposphere reducing outgoing radiation.

As concerns (ii), Spencer observes that two years from the eruption, the stratospheric aerosol effect measured by SAGE is reduced to 50%, while the ERBE net flux anomaly is already zero,

because

there are other internally-generated radiative “forcings” in the climate system measured by ERBE, probably due to natural cloud variations.

In other words, the Pinatuba effect is counterbalanced by "internal-generated radiative forcings", which indicates an even smaller climate sensitivity. In any case, the data and analysis by Spencer contradict the IPCC prediction of a climate sensitivity in the range 1.5 - 4.5 C.

This is one of many indications of a climate sensitivity smaller than 1 C, maybe smaller than

0.5 C.

ERBE measures incoming and outgoing radiation (net radiative forcing) which combined with measured temperatures gives input to determining climate sensitivity. But as Spencer points out, and I have discussed in previous posts on climate sensitivity, it may be difficult to distinguish the effect of radiative forcing from a given source (say CO2) from unknown natural sources, if the latter dominate.

tisdag 22 juni 2010

Preliminary reviews of scientific literature and surveys of climate scientists indicate striking agreement with the primary conclusions of the Intergovernmental Panel on Climate Change (IPCC):

anthropogenic greenhouse gases have been responsible for “most” of the “unequivocal” warming of the Earth’s average global temperature over the second half of the 20th century = ACC = Anthropogenic Climate Change.

Nonetheless, substantial and growing public doubt remains about the anthropogenic cause and scientific agreement about the role of anthropogenic greenhouse gases in climate change.

A vocal minority of researchers and other critics contest the conclusions of the mainstream scientific assessment, frequently citing large numbers of scientists whom they believe support their claims.

This group, often termed climate change skeptics, contrarians, or deniers, has received large amounts of media attention and wields significant influence in the societal debate about climate change impacts and policy.

The purpose of the article is to show that experts agree, but what is shown is the opposite:

Experts don't agree.

On this basis the Swedish Alliance Government announces to lead EU into a new society without fossil fuels and CO2 ACC.

Reasonable? Rational? Clever? No.

Populistic stupidity? Yes. But people are not stupid, since it is their lives and wellfare which is at stake. Do we really as Swedes have to live up to the old idea of "Swedish Stupidity"?

fredag 18 juni 2010

The previous posts lead us into the following basic scenarios of global climate with top of the atmosphere TOA temperature always - 18 C:

isothermal opaque atmosphere: surface temp: - 18 C

isothermal transparent atmosphere: surface temp: - 18 C

isentropic opaque atmosphere: surface temp: + 32 C

thermodynamic semitransparent real atmosphere: surface temp: + 15 C.

We understand that an isothermal atmosphere at - 18 C is possible both in the case of a fully transparent atmosphere without greenhouse gases GHG and fully opaque atmosphere filled by GHG. The real case at 15 C is somewhere between these extremes with a semi-transparent atmosphere with thermodynamics including latent heat/evaporation/condensation.

A simple calculation based on observed incoming = outgoing radiation = 240 W/m2 and a temperature drop dT of say 30 K from the Earth surface to TOA, gives heat transport by radiation = 4 x 30 = 120 Watts (by dQ = 4 dT), which fits with observed heat transport of 120 W by convection-evaporation/condensation (reducing the lapse rate by observed 3 K/km). This corresponds to a semi-opaque atmosphere absorbing 60 W and letting through 180 W to the Earth surface, and transporting back 120 W by convection and 120 W by radiation to TOA for radiation of 240 W to outer space at - 18 C.

We observe that in this model, increase of convective heat transport may reduce the lapse rate further and thus decrease the surface temperature. A balancing decrease of radiative heat transport fits with a smaller dT and a decrease of surface temperature. Less radiative heat transport may thus fit with increasing GHG. As noted in previous posts, the net result could be global cooling by more GHG!

Thus, not even the sign of climate sensitivity is clear, warming or cooling, not to speak of its magnitude: Whether increasing GHG will increase or decrease surface temperature will depend on the effect on incoming surface radiation and the thermodynamical heat transport including evaporation/condensation. In particular, the common belief that doubled CO2 will cause a basic global warming of 1 C, may lack scientific rationale.

Also compare with Roy Spencer's dicussion of the role of PDO in global temperature variations based on the simplest possible thermodynamic model. Spencer shows that even such a simplest model can be made to fit with observations quite well, and then indicates much smaller climate sensitivity that the simple radiative model used by IPCC to predict a basic climate sensitivity of 1 C upon doubling of atmospheric CO2 (augmented to 1.5 - 4.5 C by various feedbacks).

The conclusion is that any climate model must include thermodynamics, and the natural model is then the Navier-Stokes equations with gravitation and radiation.

torsdag 17 juni 2010

The previous posts lead us to view the thermodynamic action of the atmosphere to be similar to that of a refrigerator:

Evaporation at the ocean surface driven by incoming radiation generates cooling of the warm atmosphere above the surface.

Warm air rises by bouyancy under expansion and cooling to TOA where it releases heat by condensation for further radiation to outer space.

Cool air descends from TOA under compression and warming completing a thermodynamic refrigerating cyclic process.

In addition, some incoming heat is returned by radiation. If the radiation is blocked, more or less, by greenhouse gases, the refrigerator process must intensify to maintain heat balance. This requires more evaporation and thus more cooling of the atmosphere above the ocean surface.

The atmosphere will thus act like a refrigerator giving additional cooling under increased energy input. More greenhouse gases will thus cause global cooling!

How much cooling? Assume that now 1/4 of incoming heat is returned by radiation and 3/4

by the thermodynamic refrigerator process at a decrease of the lapse rate of 3 K/km from 10 to 7 K/km. Blocking the radiation fully would then require a further reduction of lapse by 1 K/km to 6K/km corresponding to a decrease of surface temperature by 5 K.

If the radiation was blocked by 1% the decrease of global temperature would be 0.05 K. Climate sensitivity could thus be estimated to - 0.05 K. To be compared with IPCC's + 1.5 to + 4.5 K.

To help reaching a conclusion, note that the above argument combines thermodynamics and radiation, while the claimed GHG global warming is based on radiation only. You may also recall that a refrigerator/air conditioner works by thermodynamics of expansion-evaporation-cooling + compression-condensation-warming just like in the above model of the atmosphere.

A refrigerator working by radiation only would be wonderful, but nobody has been able to

Suppose the heat transport in the troposphere changes so that less heat is radiated and more heat is transported by convection from the Earth surface, at a constant total, for example to 124 Watts by convection and 56 Watts by radiation. Will then the Earth surface temperature increase or decrease? Warming or cooling?

Tentative answer:

The temperature will drop as the intensity of evaporation/condensation increases and the troposphere lapse rate is further decreased, assuming that the tropopause temperature stays constant (assuming the stratosphere temperature does not change). The change in temperature could come from a change of lapse rate of 4/120 x 3 = 0.3 K/km resulting in a 3 K drop of surface temperature.

A shift from radiative to convective heat transfer in the troposphere can be expected by by increasing the effect of GHG greenhouse gases (mainly water vapour).

This could correspond to a decrease of surface temperature under increased cloud cover from increased GHG.

An increase of insolation by 4 Watts can by SB by expected to give an overall increase of 1 C.

The above argument uses more physics and more data than a direct application of SB argued by IPCC. Both arguments are simplistic. Which one is more realistic? Or none?

It is remarkable that not even the sign of climate sensitivity (warming or cooling by adding greenhouse gases) can be convincingly predicted by some form of mathematical analysis of the thermodynamics of an atmosphere. Or maybe it can, by a correct analysis based on computing turbulent solutions of the Navier-Stokes equations...stay tuned...

The greenhouse effect is a process by which radiative energy leaving a planetary surface is absorbed by some atmospheric gases, called greenhouse gases. They transfer this energy to other components of the atmosphere, and it is re-radiated in all directions, including back down towards the surface. This transfers energy to the surface and lower atmosphere, so the temperature there is higher than it would be if direct heating by

solar radiation were the only warming mechanism.

The Earth receives energy from the sun in the form of visible light. This light is absorbed at the Earth's surface, and re-radiated as thermal radiation. Some of this thermal radiation is absorbed by the atmosphere, and re-radiated both upwards and downwards; that radiated downwards is absorbed by the Earth's surface. Thus the presence of the atmosphere results in the surface receiving more radiation than it would were the atmosphere absent; and it is thus warmer than it would otherwise be.

This highly simplified picture of the basic mechanism needs to be qualified in a number of ways, none of which affect the fundamental process.

This mechanism is fundamentally different from that of an actual greenhouse, which works by isolating warm air inside the structure so that heat is not lost by convection.

We see that the lapse rate with an elevated surface temperature is viewed to come from radiation only, more precisely from atmospheric "re-radiation in all directions". We also see that the term "greenhouse gas" is admitted to be a (deliberately) misleading misnomer. Like the Democratic People's Republic of North Korea.

Nevertheless, this is the essence of the scientific basis of climate alarmism: Re-radiation in all directions without any thermodynamics. Convincing science? Convincing to you?

What is the physics of

the fundamental process, fundamentally different from that of a greenhouse,whichresults in the surface receiving more radiation?

What physics books describe this fundamental process? I would like to learn about this phenomenon!

Note that the "fundamental process" referred to (probably) is "photons emitted by the Earth surface" which are "being trappedb y greenhouse gases in the atmosphere" and then "re-emitted back to the Earth".

But is this the real physics of radiation as an electromagnetic wave phenomenon?

I don't think so. The idea of photons being trapped like fish in a net, is too simple. I would rather think of the situation as "dominance of the stronger over the weaker" as a flow of heat energy from higher to lower temperatures, instead of flows in both directions (at different strengths).

We thus find that radiation/conduction must be combined with thermodynamics to describe the action of the atmopshere as a global air conditioner maintaining a surface temperature of 15 C under permanent heating from the Sun, including the crucial aspect of climate sensitivity.

The above argument gives yet another indication that a simplistic estimate of basic climate sensitivity of 1 C based on radiation only, may not be close to any reality.

Different platforms for EBodyandSoul including iPad and iPhone are being investigated.

In EBodyandSoul the synthesis of mathematics, computation and application is carried further, by guiding students to the tools of modern computational mathematics in construction of computer games from basic laws of physics. This helps the student to an active feedback interplay with different mathematical models and physics, with in particular direct experience of essential input-output aspects.

söndag 6 juni 2010

The Earth surface receives about 180 Watts/m2 out of which about 60 Watts are returned

by radiation at a mean surface temperature of 15 C, and 120 Watts by convection coupled with evaporation/condensation. By Stefan-Boltzmann's radiation law the 60 Watts radiated corresponds to a temperature drop of about 15 C, which is in accordance with a radiation temperature of 0 C of the stratopause.

Suppose now the radiative properties of the atmosphere is changed by 1%, which is the estimated effect of doubled CO2. This could require an extra 0.6 Watts to be radiated, which by Stefan-Boltzmann would correspond to an increase of surface temperature 0.15 C.

This argument suggests a climate sensitivity 0.15 C. With an even more simplistic argument based on Stefan-Boltzmann, IPCC suggests instead 1 C, which is elevated by feedbacks

to an alarming 3 C. Starting instead with 0.15 C gives no reason for alarm.

Which argument do you think is more correct? Both are simplistic and do not require more than common sense to evaluate.

It is also very remarkable that the research is based on a preconcieved postulate of "man´s ever-increasing impact on the climate system through emission of greenhouse gases". Note the clever use of the term "ever-increasing" without quantitative information, which is meant to signal alarm without any need of providing scientific evidence, following the standard of IPCC. But what will happen to the Bolin Centre if the effect of CO2 shows to be neglible?